docs: def list_equivalencies(self):
          """Lists the possible equivalencies associated with this unit object
  
          Examples
          --------
          >>> from unyt import km
          >>> km.units.list_equivalencies()
          spectral: length <-> spatial_frequency <-> frequency <-> energy
          schwarzschild: mass <-> length
          compton: mass <-> length
          """
          from unyt.equivalencies import equivalence_registry
  
          for k, v in equivalence_registry.items():
              if self.has_equivalent(k):
                  print(v())